Thermoelectric Generator (TEG) Description

What is a Thermoelectric Generator (TEG)?

Thermoelectric Generators or TEGs are devices that are used to convert heat energy to electricity. Using the "Seebeck Effect" electricity
can be generated if there is temperature differential between the two sides of a thermoelectric generator module. As these systems depend upon a temperature
differential to provide electricity, the modules are often combined with a consistent heat source, such as natural gas or propane, for remote power generation or waste
heat recovery. They are often used in remote locations where power is required but solar energy is insufficient, such as oil pipelines to power remote telemetry and data
collection.

Thermoelectric generators or TEGs are devices that utilize one or more thermoelectric modules as the primary components, followed by a cooling system
that can be either passive or active, such as an open air heat sink, fan cooled heat sink, or fluid cooled. These components are then fabricated into an assembly to
function as one unit called a TEG. A TEG consists of a heat receiving surface as well as a heat exiting surface. The heat exiting surface can be actively or passively cooled. Most High Power thermoelectric generators are actively cooled using hydronic cooling systems containing water or glycol. Tegpro, a Vermont based company are experts in Thermoelectric Generator design. They have been working on self-powered heating system technologies since 2008.

How do Thermoelectric Generators (TEGs) work?

When heat is applied to the hot side of a Thermoelectric Generator and a much cooler temperature to the heat exiting area, electricity is produced. Almost any heat source can be used to generate electricity, such as boilers, furnaces and portable heaters. In addition the efficiency of
any device or machine that generates heat as a by-product can be drastically improved by recovering the energy lost as heat. Tegprodesigns heating systems that utilize the coldest part of a building against the hottest part, the heating system to generate electricty. Using this method any heat lost, is lost to the area being heated ensuring a highly efficient design.

What is a thermoelectric generator module?

Thermoelectric generator modules are solid-state integrated circuits that employ an established thermoelectric effect known as the
Seebeck effect. It is the Seebeck effect that is responsible for electrical power generation. The thermoelectric generator module or TEM is the heart of a thermoelectric generator or TEG.

How are thermoelectric generator modules made?

The construction of a thermoelectric generator module consists of pairs of p-type and n-type semiconductor materials with a high thermoelectric coefficient. Although many different materials can be used, a bismuth telluride alloy is the most common material in use today. This material is sliced into small blocks, one forms the p-type conductor and the other the n-type conductor. Each pair forms a thermoelectric couple (TEC).

Most others use many thermoelectric couples that are sandwiched between two pieces of non-electrically conductive materials to produce a thermoelectric generator module. It is also necessary for this material to be thermally conductive to ensure a good heat transfer, usually two thin ceramic wafers are used. This now forms what is called a thermoelectric module. Tegpro adds a layers of graphite to the exterior of their ceramic wafers allowing the thermoelectric generator module to be installed with the need of a thermally conductive paste.

Now, if a thermoelectric generator module is being manufactured for use in a thermoelectric generator (TEG) it has its own unique requirements. First they need to have lowest internal resistance possible and high temperature solder connecting the wires. The solder reflow temperature has to be able to withstand temperatures greater than 400 C for high temperature thermoelectric generator modules such as the one's that Tegpro manufactures. In addition, heat resistant insulation made from PTFE is used to coat the wires. Braided fiberglass sleeves can also be slipped over the wires providing further protection from the high heat.